The Carboniferous-Lower Permian's Sedimentary Facies Characteristics And Their Conformity Implications For The Reservoir In The Southern Margin Of Santanghu Basin

Santanghu basin is the composite and transform-based mountain basin located in the eastern part of Xinjiang, beside the southern edge of Siberian plate. The Carboniferous' oil and gas exploration in the area has got greater breakthrough in recent years. The study to sedimentary facies and their controlling factors of reservoir can be provided objective theoretical basis and contribute to get further oil and gas exploration outcome.On the basis of profile observation, description of core, observation of conventional and casting thin section, from the stratigraphic division and correlation and characteristics of sedimentary environment, combined with advanced analytical tools support, types of sedimentary facies, development characteristics, and vertical and horizontal distribution are analyzed. Then, the development of sedimentary facies patterns are set up. Through the reservoir rock, reservoir studies, reservoir evaluation and classification are studied. The favorable reservoir facies and control factors are pointed out.Synthesized various methods and combined with previous data, this paper argues that the Lower Carboniferous consists of Donggulubasitao group, Jiangbasitao group, upper Carboniferous includes Batamayineishan group and Haerjiawu group. Kalagang group be classified in early Permian. The types of rocks includes clastic rocks and volcanic rocks. Clastic rocks are distributed in various profiles and layers. Volcanic rock is also distributed in broad area, even to occupy the main post at Haerjiawu group and Kalagang group. The main are volcanic lava and pyroclastic rock.From the lithological, palaeontological markers, geochemical signs, heavy minerals and also several aspects' facies signs, the sedimentary facies are divided in the study area. The main types of sedimentary facies include marine facies, estuarine facies facies, delta facies, shallow shelf facies, volcanic basin facies, lake facies. Vertically, the water of deposition bodies became shallower, sedimentary rocks reduced, volcanic rocks developed, and marine-continental transitional facies transform to continental facies. Changes in the horizontal are not enough obvious. It can be obtained that the north-west body of water is more shallows than south-east body of water, sediment is thicker at both ends, and the central area's volcanic eruption seems more violent. There are land-based sources barrier-free marine, land-based sources barrier marine, delta volcanic basin several facies models. Most of the Carboniferous volcanic reservoir is volcanic rock reservoir. The volcanic breccia is better than others, as well as as well as in the outbreak phase than others phases. Reservoir space belongs to dual structure porosity what are the cracks and the pore. Carboniferous reservoirs are lowporosity and low permeability reservoir in this area on the whole.